1. Field of the Invention
The invention relates to a method of operation of a coking plant having coke chambers for the coking of coal by dry distillation, and to a coking plant adapted for operation by the method of the invention. The invention is particularly concerned with the reduction or prevention of the emission to the atmosphere of undesirable gas and dust, etc.
2. Description of the Prior Art
In the manufacture of coke, continuous efforts have been made to prevent as far as possible emission of smoke, soot and dust into the atmosphere while the coke chambers are being charged with coal. A number of proposals to this end are described in British patent specification 1,291,096, particularly that the steam is supplied to the steam injector in the ascension pipe of the chamber concerned while it is being charged through the charging holes in the roof. In the ascension pipe a sub-atmospheric pressure of 2 to 6 mm water column is thus created during charging. After levelling and closing of the charging holes, the steam supply to the injectors in the ascension pipe is cut off, and coking is initiated.
Notwithstanding all the precautions taken, such as systematic cleaning of the door posts, and the doors themselves, it has proved not to be feasible to seal the two doors at the ends of each of the horizontal oven chambers sufficiently. In the initial phase of the coking process, considerable gas formation occurs in the oven chambers, together with a slight super-atmospheric pressure. This overpressure--depending on the pressure set in the gas collecting main--drops within 5 hours from about 10 to 0 mm water column, measured at the bottom of the chamber door, while by the end of the coking time a sub-atmospheric pressure of about -1 mm prevails. (See also W. Litterscheidt's contribution to the "Handbuch des Kokereiwesens", published by Dr. Otto Grosskinsky, Vol. I, 1955 Dusseldorf, page 217--where it is mentioned that the level of maximum pressure and the variation of pressure, in the chamber depend on the type of coal and on the degasification conditions). In the initial stage of the coking process there is consequently an over-pressure, which escapes through unintentional leakage past doors etc., and is perceived as disagreeable smoke and fumes. Even if steam injection is applied during charging as described above, the undesirable emission continues.